As part of the manufacturing process of integrated circuits, the integrated circuits typically undergo reliability testing. One such reliability test is commonly known as burn-in. Burn-in testing involves the testing of an integrated circuit for an extended period of time while the temperature of the integrated circuit is elevated above room temperature. Operating the integrated circuit while at an elevated temperature for an extended period stresses the integrated circuit and may cause a failure that would not occur at room temperature. However, semiconductor manufacturers have the cost savings goal of testing, and screening out, defective integrated circuits as quickly and as early as possible in the manufacturing process.
One way of reducing the time required to conduct burn-in testing is to operate the integrated circuit during burn-in using a higher power supply voltage than normal. This will cause accelerated aging of the integrated circuit, thus causing the integrated circuit to fail, if it is going to, more quickly than testing at elevated temperatures but with a normal power supply voltage.
Integrated circuits are fabricated using a manufacturing process technology that is designed to operate optimally at a particular power supply voltage. However, some systems, such as for example, a personal computer, may require a power supply voltage that is different than the power supply voltage for which the integrated circuit was designed to operate. Because it is desirable to be able to operate certain integrated circuits in a variety of systems requiring different supply voltages, the integrated circuit may include an onboard voltage regulator that provides the correct internal power supply voltage to the circuits of the integrated circuit substantially independent of the system's power supply voltage.
One problem with using a voltage regulator is that burn-in cannot be conducted on the integrated circuit using higher than normal power supply voltages. Thus, the time required to perform burn-in is extended.
Therefore, a need exists for a voltage regulator that allows a higher than normal power supply to be provided to the circuits of an integrated circuit during burn-in, while providing a normal power supply voltage during normal operation.